Stabilisation of belite prepared from modified limestone waste sludge

Abstract

Presenting work deals with the use of waste materials-waste sludge from mining and washing of limestone and waste material from acetylene gas cylinders containing mainly tobermorite and xonotlite. Both materials were characterized by X-ray powder diffraction, laser granulometry and chemical analysis. After drying and milling of raw materials, they were mixed together and homogenised resulting in 3 sample series with different ratios of these materials. The mixtures were then burned at 1150°C and 1350°C and the main products formed were lime, dicalcium silicate, wollastonite, pseudowollastonite and gehlenite. To preserve hydraulically active belite, K2O as stabilizing agent was added in amount of 1 and 3 wt. %. Burned products were studied by means of X-ray diffraction and optical microscopy. Also hydration was observed.